System and method for removing deposits

Abstract

To provide a deposit removal system capable of appropriately operating a soot blower and sufficiently removing deposit adhered to a heat transfer surface of a heat exchanger.SOLUTION: A deposit removal system 70 for removing dust adhered to heat transfer surfaces of superheaters 41-43 recovering heat from exhaust gas by using a soot blower 71 includes: a prediction range setting section 75a setting a prediction range of removal amount of dust; removal amount measurement means (73, 75b) measuring the removal amount of dust removed by the soot blower 71; and operation control means (72, 75c, 75d) controlling an operation of the soot blower 71 so that the measured removal amount of dust falls within the prediction range.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a deposit removal system and method for removing deposits attached to a heat transfer surface of a heat exchanger that recovers heat from exhaust gas by using a soot blower. [Background technology]

[0002] In recent years, it has become important to increase the amount of electricity generated at waste incineration facilities and other facilities that are equipped with power generation equipment. Power generation at waste incineration facilities is carried out by recovering heat in a boiler from the high-temperature exhaust gas generated by the combustion of waste in a combustion furnace, generating steam at a specified temperature and pressure, and introducing the steam into a turbine generator.

[0003] The boiler has a radiation chamber and a convection heat transfer chamber. A radiation heat transfer tube is disposed in the radiation chamber as a radiation heat transfer surface, and for example, a superheater is disposed in the convection heat transfer chamber as a convection heat transfer surface. The superheater is configured by arranging a group of heat transfer tubes (superheater tubes) in the horizontal direction in multiple stages in the vertical direction.

[0004] Exhaust gas from combustion furnaces contains soot (dust) that includes corrosive components and heavy metals, etc. As a result, as operation progresses, dust gradually adheres to and accumulates on the boiler's radiative and convective heat transfer surfaces, causing problems such as a decline in heat recovery performance, blockage of gas flow paths, and corrosion of heat transfer tubes, making it difficult to continue normal operation.

[0005] Therefore, by installing a soot blower as a dust removal device that can remove dust during operation, it is possible to continue normal operation. Examples of soot blowers include steam soot blowers (see, for example, Patent Document 1) and shock pulse soot blowers (see, for example, Patent Document 2).

[0006] The steam type soot blower according to Patent Document 1 comprises a soot blower body equipped with an injection nozzle for injecting water steam, and a drive device for driving the soot blower body to feed into the exhaust gas passage of the boiler or to pull it out from the exhaust gas passage of the boiler. This steam type soot blower is configured to remove dust adhering to the heat transfer tubes by feeding the soot blower body into the exhaust gas passage of the boiler using the drive device and injecting water steam from the injection nozzle provided on the soot blower body toward the heat transfer tubes of the boiler.

[0007] The shock pulse soot blower of Patent Document 2 comprises a container having an opening and a sealing body that covers the opening of the container, and is configured to fill the container with combustible material, burn the filled combustible material to increase the pressure inside the container, thereby destroying the sealing body and generating a pressure wave, and use the generated pressure wave to remove dust adhering to the heat transfer tubes of a boiler. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Utility Model Application Publication No. 60-196132 [Patent Document 2] International Publication No. 2020 / 225984 Summary of the Invention [Problem to be solved by the invention]

[0009] In the steam soot blower disclosed in Patent Document 1, the soot blower body is sent into the boiler's exhaust gas passage by a driving device, and water steam is sprayed from an injection nozzle provided on the soot blower body, and this operation for dust removal is performed once periodically at regular intervals.

[0010] In the shock pulse soot blower disclosed in Patent Document 2, the opening of a container is sealed with a seal, the container is filled with combustible material, the filled combustible material is ignited and burned, and the pressure inside the container is increased to destroy the seal and generate a pressure wave.This dust removal operation is performed periodically once at regular intervals.

[0011] As described above, operating the soot blower once periodically at a fixed time interval may be sufficient to remove dust, but may not be sufficient to remove dust depending on the state of dust adhesion to the heat transfer tube. Therefore, it is possible to operate the soot blower continuously multiple times periodically at fixed time intervals. However, even though a single operation of the soot blower may be sufficient to remove dust, it is uneconomical to operate the soot blower continuously periodically.

[0012] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an adhesion removal system and an adhesion removal method that can properly operate a soot blower while sufficiently removing adhesions adhered to the heat transfer surface of a heat exchanger. [Means for solving the problem]

[0013] The characteristic configuration of the deposit removal system according to the present invention for solving the above problem is as follows: A deposit removal system that removes deposits attached to a heat transfer surface of a heat exchanger that recovers heat from exhaust gas using a soot blower, A prediction range setting means for setting a prediction range of the amount of removal of the deposit; A removal amount measuring means for measuring the amount of the deposit removed by the soot blower; An operation control means for controlling the operation of the soot blower so that the measured amount of removed deposit falls within the predicted range; The purpose of this project is to provide the following:

[0014] According to the deposit removal system of this configuration, the predicted range of the amount of removed deposits is set by the predicted range setting means. Also, the amount of removed deposits removed by the soot blower is measured by the removal amount measuring means. Then, the operation of the soot blower is controlled by the operation control means so that the measured amount of removed deposits is within the predicted range of the amount of removed deposits. For example, even if the soot blower is operated periodically once at a certain time interval, if the measured amount of removed deposits is within the predicted range of the amount of removed deposits, such periodic operation of the soot blower is performed once. On the other hand, if the measured amount of removed deposits falls outside the predicted range of the amount of removed deposits, the operation of the soot blower is controlled so that the amount of removed deposits falls within the predicted range, for example, by shortening the interval between the deposit removal operation by the soot blower or by performing the deposit removal operation by the soot blower multiple times in succession. Therefore, the soot blower can be operated appropriately, and the amount of attached deposits within the predicted range can be reliably removed, and the deposits can be sufficiently removed.

[0015] In the deposit removal system according to the present invention, It is preferable that the operation control means shortens an interval between operations of removing deposits by the soot blower when the measured amount of removed deposits is greater than an upper limit of the prediction range.

[0016] For example, in the case where excessive deposits have adhered and accumulated on the heat transfer surface of a heat exchanger beyond prediction, when the excessive deposits are removed by operating the soot blower, the amount of deposits removed measured by the removal amount measuring means may be greater than the upper limit of the predicted range of the amount of deposits to be removed. In such a case, according to the deposit removal system of this configuration, the interval between deposit removal operations by the soot blower is shortened, in other words, the number of times the soot blower is operated within a specified time is increased, so that even if deposits have adhered and accumulated beyond prediction, the deposits can be quickly removed and heat recovery performance can be quickly restored.

[0017] In the deposit removal system according to the present invention, It is preferable that the operation control means, when the measured amount of removed deposits is smaller than a lower limit of the prediction range, performs the deposit removal operation by the soot blower a plurality of times in succession.

[0018] For example, when a deposit is firmly attached and accumulated on the heat transfer surface of a heat exchanger, operation of the soot blower once periodically at a fixed time interval may not remove the deposit sufficiently, and the amount of the deposit removed measured by the removal amount measuring means may be smaller than the lower limit of the predicted range of the amount of the deposit removed. In such a case, according to the deposit removal system of this configuration, the deposit removal operation is performed by the soot blower multiple times in succession, so that even if the deposit is firmly attached and accumulated, the deposit can be quickly removed and the heat recovery performance can be quickly restored.

[0019] Next, the characteristic configuration of the deposit removal method according to the present invention for solving the above problems is as follows: A method for removing deposits attached to a heat transfer surface of a heat exchanger that recovers heat from exhaust gas by using a soot blower, comprising the steps of: a prediction range setting step of setting a prediction range of the amount of removal of the deposit; a removal amount measuring step of measuring the amount of the deposit removed by the soot blower; an operation control step of controlling the operation of the soot blower so that the measured amount of removed deposit falls within the predicted range; The purpose of this study is to encompass the above.

[0020] According to the deposit removal method of this configuration, a predicted range of the amount of removed deposits is set in a predicted range setting step. Also, the amount of removed deposits removed by the soot blower is measured in a removal amount measuring step. Then, in the operation control step, the operation of the soot blower is controlled so that the measured amount of removed deposits is within the predicted range of the amount of removed deposits. For example, if the measured amount of removed deposits is within the predicted range of the amount of removed deposits even when the soot blower is operated periodically once at a certain time interval, such periodic operation of the soot blower is performed. On the other hand, if the measured amount of removed deposits falls outside the predicted range of the amount of removed deposits, the operation of the soot blower is controlled so that the amount of removed deposits falls within the predicted range, for example, by shortening the interval between the deposit removal operations by the soot blower or by performing the deposit removal operations by the soot blower multiple times in succession. Therefore, the soot blower can be operated appropriately, and the amount of attached deposits within the predicted range can be reliably removed, and the deposits can be sufficiently removed.

[0021] In the method for removing deposits according to the present invention, When the measured amount of removed deposits is greater than the upper limit of the prediction range, it is preferable that in the operation control step, the operation of the soot blower is controlled so as to shorten the interval between deposit removal operations by the soot blower.

[0022] For example, in the case where excessive deposits have adhered and accumulated on the heat transfer surface of the heat exchanger beyond prediction, when the excessive deposits are removed by operating the soot blower, the amount of deposits removed measured in the removal amount measurement process may be greater than the upper limit of the predicted range of the amount of deposits removed. In such a case, according to the deposit removal method of this configuration, the interval between deposit removal operations by the soot blower is shortened in the operation control process, in other words, the number of times the soot blower is operated within a specified time is increased, so that even if deposits have adhered and accumulated beyond prediction, the deposits can be quickly removed and heat recovery performance can be quickly restored.

[0023] In the method for removing deposits according to the present invention, When the measured amount of removed deposits is smaller than the lower limit of the predicted range, it is preferable that in the operation control process, the operation of the soot blower is controlled so that the deposit removal operation is performed by the soot blower multiple times in succession.

[0024] For example, when there is strong adhesion and buildup of deposits on the heat transfer surface of a heat exchanger, the amount of deposits removed measured in the removal amount measurement step may not be sufficiently removed by operating the soot blower once periodically at a fixed time interval, and the amount of deposits removed may be smaller than the lower limit of the predicted range of the amount of deposits removed. In such a case, according to the deposit removal method of this configuration, the operation control step involves the soot blower performing the deposit removal operation multiple times in succession, so that even if the deposits are strong and buildup, the deposits can be quickly removed and heat recovery performance can be quickly restored. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a combustion treatment facility equipped with a deposit removal system according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart showing a procedure for controlling the operation of a soot blower performed in a dust removal method according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a graph showing the amount of dust removed for each operation of the sootblower relative to the predicted range of dust removal amounts. [Figure 4] FIG. 4 is a flowchart showing a procedure for controlling the operation of a soot blower in the dust removal method according to the first alternative embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram showing a schematic configuration of a combustion treatment facility equipped with a deposit removal system according to another embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The present invention will be described below with reference to the drawings. In the following embodiments, a deposit removal system and a deposit removal method applied to a boiler installed in parallel with a combustion furnace of a waste incineration treatment facility will be described as an example. However, the present invention is not intended to be limited to the embodiments described below or the configurations shown in the drawings.

[0027] <Overall configuration of waste incineration treatment facility> FIG. 1 is a schematic diagram showing a schematic configuration of a combustion treatment facility 1 equipped with an attachment removal system 70 according to an embodiment of the present invention. As shown in FIG. 1, the combustion treatment facility 1 mainly includes a combustion material receiving section 2, a combustion furnace 3, a boiler 4, and a separate economizer 5. In this combustion treatment facility 1, the combustion material (e.g., waste such as urban waste) received in the combustion material receiving section 2 is combusted in the combustion furnace 3. The exhaust gas generated by the combustion in the combustion furnace 3 is introduced into the boiler 4 and the separate economizer 5 by the induction action of an induction fan (not shown) and heat is recovered. Thereafter, the exhaust gas is cooled in a temperature reducing tower (not shown) and introduced into a bag filter (not shown) together with a neutralizing agent, etc., and after acid gas components and soot (dust), etc. are removed in the bag filter, it is introduced into a denitration device (not shown) and released to the outside through a chimney (not shown) after denitration treatment. The combustion treatment facility 1 is provided with a power generation facility (not shown) so that steam generated in the boiler 4 is introduced into the power generation facility to generate electricity.

[0028] <Boiler> The boiler 4 includes a first radiant chamber 21, a second radiant chamber 22, and a convective heat transfer chamber 23, which are partitioned in this order from the upstream side to the downstream side in the exhaust gas flow direction.

[0029] The first radiation chamber 21 extends in the vertical direction so as to be connected to the combustion chamber of the combustion furnace 3. The first radiation chamber 21 and the second radiation chamber 22 are connected via a first turning section 31. The second radiation chamber 22 extends in the vertical direction so as to be adjacent to the first radiation chamber 21. The second radiation chamber 22 and the convection heat transfer chamber 23 are connected via a second turning section 32. The convection heat transfer chamber 23 extends in the vertical direction so as to be adjacent to the second radiation chamber 22.

[0030] In the boiler 4, the exhaust gas introduced from the combustion furnace 3 flows from the bottom to the top of the first radiation chamber 21, passes through the first turning section 31, flows further from the top to the bottom of the second radiation chamber 22, and then flows from the bottom to the top of the convection heat transfer chamber 23 through the second turning section 32.

[0031] In the first radiation chamber 21 and the second radiation chamber 22, a large number of radiation heat transfer tubes that form a radiation heat transfer surface for receiving radiant heat from the exhaust gas and generating steam are disposed.

[0032] In the convection heat transfer chamber 23, a plurality of superheaters 41, 42, 43 each having the same type of heat exchanger are arranged at a predetermined interval from each other. In this example, the tertiary superheater 41, the secondary superheater 42, and the primary superheater 43 are arranged in this order from the upstream side to the downstream side in the exhaust gas flow direction. The superheaters 41, 42, 43 each include a heat transfer tube group in which a plurality of heat transfer tubes arranged in the horizontal direction are arranged in multiple stages in the height direction, and the heat transfer tubes form a convection heat transfer surface, and are configured to generate steam by heat exchange with the exhaust gas and further superheat it. Here, an example has been shown in which a plurality of superheaters 41, 42, 43 consisting of the same type of heat exchanger are arranged in the convection heat transfer chamber 23, but this is not limited to this. Different types of heat exchangers, for example, screen tubes, superheaters, evaporator tubes, economizers, etc., may be arranged in the convection heat transfer chamber 23 from the upstream side to the downstream side in the exhaust gas flow direction with a predetermined distance between them in an appropriate arrangement without being limited to the arrangement described above.

[0033] <Separate economizer> The boiler 4 and the separate economizer 5 are connected via a third deflection section 33. The separate economizer 5 includes a convection heat transfer chamber 24 extending in the vertical direction so as to be adjacent to the convection heat transfer chamber 23. In the convection heat transfer chamber 24, a plurality of economizer sections 51, 52, and 53 are arranged at predetermined intervals from each other. In this example, the first economizer section 51, the second economizer section 52, and the third economizer section 53 are arranged in this order from the upstream side to the downstream side in the exhaust gas flow direction. The economizer sections 51, 52, and 53 include an economizer water tube group in which a plurality of economizer water tubes arranged in the horizontal direction are arranged in multiple stages in the height direction.

[0034] <Transportation equipment> A conveying device 60 is disposed below the convection heat transfer chamber 23 in the boiler 4 and below the second turning section 32. The conveying device 60 is configured to include a casing 61 and a conveying mechanism 62 disposed in the casing 61. Dust dropping from the convection heat transfer chamber 23 passes through the second turning section 32 and the casing 61 and is dropped and placed on the conveying mechanism 62. Similarly, a conveying device 60 is disposed below the convection heat transfer chamber 24 in the separate economizer 5 and below the bottom of the separate economizer 5. Dust dropping from the convection heat transfer chamber 24 passes through the bottom of the separate economizer 5 and the casing 61 and is dropped and placed on the conveying mechanism 62. The dust placed on the conveying mechanism 62 is conveyed to a fly ash treatment facility 64 via a conveying line 63.

[0035] <Deposit removal system> The deposit removal system 70 provided in the combustion treatment facility 1 configured as described above comprises a shock pulse type soot blower 71 arranged in the boiler 4 so that the pressure wave discharge outlet is located between the tertiary superheater 41 and the second turning section 32 in the convection heat transfer chamber 23, a control panel 72 that controls the operation of the soot blower 71, a distance meter 73 installed on the conveying device 60 arranged below the second turning section 32, and a controller 75 communicatively connected to the control panel 72.

[0036] <Soot Blower> As the soot blower 71, for example, the deposit removal device disclosed in International Publication No. 2020 / 225984 is used. Although detailed explanation by illustration is omitted, the soot blower 71 is briefly described as comprising a container having an opening and a sealing body that blocks the opening of the container, and is configured to be able to perform an attachment removal operation (pressure wave driving operation) that removes attachments (dust) attached to the heat transfer tube by filling the container with a combustible material, burning the filled combustible material, and increasing the pressure in the container, thereby destroying the sealing body and generating a pressure wave by using the generated pressure wave. Furthermore, the soot blower 71 is equipped with a switching mechanism that switches between a state in which the sealing body is pressed against the opening of the container and a state in which it is not pressed against the opening of the container, and a sealing body supply mechanism that supplies the sealing body to the opening of the container when the sealing body is not pressed against the opening of the container, and is configured to be able to perform a single operation in which the adhesion removal operation is performed periodically once at a fixed interval, and a continuous operation (continuous shooting) in which the adhesion removal operation is performed multiple times in succession by cooperation between the switching mechanism and the sealing body supply mechanism. Note that instead of the shock pulse type soot blower, for example, a steam type soot blower such as that disclosed in Japanese Utility Model Laid-Open Publication No. 60-196132 may be adopted as the soot blower 71.

[0037] Here, "continuous operation" means continuous operation (operation in which pressure waves are continuously fired) in which the previous operation (previous adhesion removal operation) and the next operation (next adhesion removal operation) are performed continuously without any interruption, as well as continuous operation including preparation time (operation in which pressure waves are fired intermittently). "Continuous operation including preparation time" means operation in which a preparation time (for example, about 1 to 10 minutes) is required for preparation for the generation of the next pressure wave between the previous operation and the next operation, such as supplying a new sealing body that has not been destroyed to the opening of the container in place of the sealing body destroyed after the previous pressure wave generation, or filling the container with a flammable material, but without intentionally leaving a certain time between the previous operation and the next operation, and multiple operations are performed continuously as a whole within a specified time.

[0038] <Control panel> The control panel 72 is mainly composed of a computer equipped with a CPU, memory, storage, I / O ports, peripheral devices, etc. The control panel 72 controls the operation of the soot blower 71, such as the switching operation between a pressing state and a non-pressing state by the switching mechanism, the sealing body supply operation by the sealing body supply mechanism, the filling operation of the container with a flammable material, the ignition operation of the filled flammable material, etc.

[0039] <Distance meter> The distance meter 73 is installed in the casing 61 so as to be located above the transport mechanism 62 so as to be able to measure the dust transported by the transport mechanism 62 as a measurement target. For example, a laser distance meter that measures distance by measuring the phase of modulated laser light can be used as the distance meter 73. The pile height H(X) of the dust transported by the transport mechanism 62 on the transport mechanism 62 can be calculated from the difference between the vertical distance L(A) to the dust measured by the distance meter 73 and the vertical distance L(B) to the transport surface of the transport mechanism 62 measured by the distance meter 73. Note that the distance L(B) is determined when the distance meter 73 is installed in the casing 61, and is a fixed value that does not change once it is measured by the distance meter 73.

[0040] <Controller> The controller 75 is mainly composed of a computer including a CPU, a memory, a storage, an I / O port, peripheral devices, and the like. The controller 75 performs the functions of a prediction range setting unit 75a, a removal amount calculation unit 75b, a comparison calculation unit 75c, and an operation control unit 75d by having the CPU read and execute a predetermined program stored in the memory. The controller 75 may be, for example, a distributed control system (DCS), a programmable logic controller, a server, a workstation, or other computer devices. The functions of the prediction range setting unit 75a, the removal amount calculation unit 75b, the comparison calculation unit 75c, and the operation control unit 75d will be described together with the description of a flowchart (see FIG. 2) showing the procedure of the operation control of the soot blower 71 described later. The prediction range setting unit 75a corresponds to the "prediction range setting means" of the present invention. The configuration including the range meter 73 and the removal amount calculation unit 75b corresponds to the "removal amount measurement means" of the present invention. The configuration including the control panel 72, the comparison calculation unit 75c, and the operation control unit 75d corresponds to the "operation control means" of the present invention.

[0041] Fig. 2 is a flowchart showing the procedure for controlling the operation of the soot blower 71 performed in a dust removal method according to one embodiment of the present invention. The procedure for controlling the operation of the soot blower 71 shown in the flowchart of Fig. 2 will be described below with reference to Fig. 1. In Fig. 2, the symbol "S" represents a step (the same applies to Fig. 4). At the start of the flowchart of Fig. 2, it is assumed that the soot blower 71 is operating once periodically at a fixed time interval.

[0042] FIG. 3 is a graph showing the dust removal amount for each operation of the soot blower 71 with respect to the predicted range of the dust removal amount. The predicted range setting unit 75a shown in FIG. 1 sets the predicted range of the dust removal amount as shown in FIGS. 3(a) and (b) based on past data of the dust removal amount removed by the soot blower 71 in the boiler 4. In FIGS. 3(a) and (b), the vertical axis represents the dust removal amount by the soot blower 71, and the horizontal axis represents time. In FIGS. 3(a) and (b), when the operation of the soot blower 71 is performed at a predetermined time, the predicted range setting unit 75a sets a predicted range upper limit line La indicating the upper limit of the predicted range and a predicted range lower limit line Lb indicating the lower limit of the predicted range as the predicted range of the dust removal amount. The area between the predicted range upper limit line La and the predicted range lower limit line Lb is the predicted range.

[0043] Further, FIG. 3(a) shows the relationship between the dust removal amount and the operation execution timing when the dust removal amount Q(X) calculated by the removal amount calculation unit 75b is greater than the upper limit of the predicted range set by the predicted range setting unit 75a immediately after the operation of the soot blower 71 performed at time t3. On the other hand, FIG. 3(b) shows the relationship between the dust removal amount and the operation execution timing when the dust removal amount Q(X) calculated by the removal amount calculation unit 75b is less than the lower limit of the predicted range set by the predicted range setting unit 75a immediately after the operation of the soot blower 71 performed at time t3.

[0044] <S1: Predicted Range Setting Step> In step S1 in the flowchart shown in FIG. 2, the predicted range setting unit 75a sets a predicted range upper limit line La and a predicted range lower limit line Lb as the predicted range of the dust removal amount as shown in FIG. 3(a) based on past data of the dust removal amount removed by the soot blower 71 in the boiler 4.

[0045] In FIG. 3(a), the operation interval of the soot blower 71 is relatively long from time t1 to t3, whereas the operation interval of the soot blower 71 is relatively short from time t3 onwards. Also, since the operation interval of the soot blower 71 is relatively long from time t1 to t3, the amount of dust removed by each dust removal operation by the soot blower 71 is relatively large. Therefore, the prediction range of the dust removal amount is set to a high level overall. In contrast, since the operation interval of the soot blower 71 is relatively short from time t3 onwards, the amount of dust removed by each dust removal operation by the soot blower 71 is relatively small. Therefore, the prediction range of the dust removal amount is set to a low level overall. Note that the "operation interval" is determined as an interval in hours for the operation of the soot blower 71, and is the time interval between the time of the previous operation of the soot blower 71 and the time of the next operation of the soot blower 71.

[0046] <S2~S3> In the flowchart of FIG. 2, when the time to operate the soot blower 71, for example, time t2 (see FIG. 3(a)) is reached ("YES" in S2), the operation control unit 75d transmits an operation command signal to the control panel 72 (S3). The control panel 72 controls the soot blower 71 so that the soot blower 71 performs a dust removal operation, triggered by the operation command signal from the operation control unit 75d. That is, the opening of the container is sealed with a seal, the container is filled with a combustible material, the filled combustible material is ignited and burned, and the pressure inside the container is increased to break the seal and generate a pressure wave. As a result, a pressure wave is released from the pressure wave release port into the convection heat transfer chamber 23 of the boiler 4, and the dust attached and accumulated on the heat transfer tube of the tertiary superheater 41 is mainly removed by the wind pressure and vibration caused by the pressure wave. In this way, the dust attached to the heat transfer tube can be removed over a wide area without damaging the heat transfer tube.

[0047] <s4> In step S4, it is determined whether or not the amount of dust removed by the operation of the soot blower 71 carried out at time t2 is within the prediction range shown in FIG. 3(a) and set by the prediction range setting unit 75a.

[0048] <Removal amount measurement process> That is, when the distance L(A) to the dust transported by the transport mechanism 62 is measured by the distance meter 73 for a certain time (T) immediately after the operation of the soot blower 71 at time t2, the removal amount calculation unit 75b shown in Figure 1 calculates the pile height H(X) of the dust transported by the transport mechanism 62 from the measured distance L(A) and the fixed distance L(B), and calculates the amount of dust removed by the operation of the soot blower 71 Q(X) from the following equation (1) based on the calculated dust pile height H(X), the effective width W of the transport mechanism 62 at which dust can actually be loaded, and the dust transport speed V by the transport mechanism 62 during the time (T), and if necessary, multiplying by an appropriate correction coefficient α taking into account the fact that dust is not uniformly loaded on the transport mechanism 62, etc. Then, the comparison calculation unit 75c compares the dust removal amount Q(X) calculated by the removal amount calculation unit 75b with the prediction range set by the prediction range setting unit 75a (see FIG. 3(a)). Q(X) = α·H(X)·W·V·T ···(1)

[0049] In the example shown in FIG. 3(a), since the dust removal amount Q(X) measured immediately after time t2 is within the predicted range ("YES" in S4), the process returns to step S1 and the operation of the soot blower 71 is continued, which is performed periodically once at regular intervals.

[0050] In step S2 after step S1, when reaching, for example, time t3 (see Fig. 3(a)), which is the time to operate the soot blower 71, (when "YES" in S2), the operation control unit 75d transmits an operation command signal toward the control panel 72 (S3). The control panel 72 uses the operation command signal from the operation control unit 75d as a trigger to control the soot blower 71 so that the soot blower 71 performs a dust removal operation as described above, generating a pressure wave. As a result, mainly, the dust adhering and depositing on the heat transfer tubes of the tertiary superheater 41 is removed.

[0051] <S4~S5> The comparison operation unit 75c determines whether the dust removal amount Q(X) calculated by the removal amount calculation unit 75b is within the prediction range shown in Fig. 3(a) set by the prediction range setting unit 75a immediately after the operation of the soot blower 71 performed at time t3 (S4). In the example shown in Fig. 3(a), since the dust removal amount Q(X) measured immediately after time t3 is outside the prediction range (when "NO" in S4), the process proceeds to step S5. In step S5, the comparison operation unit 75c determines whether the dust removal amount Q(X) measured immediately after time t3 is greater than the upper limit of the prediction range shown in Fig. 3(a) (S5).

[0052] <S6: Prediction range setting process> In the example shown in Fig. 3(a), since the dust removal amount Q(X) measured immediately after time t3 is greater than the upper limit of the prediction range shown in Fig. 3(a) (when "YES" in S5), the prediction range setting unit 75a sets, shortly after time t3 and thereafter, as the prediction range of the dust removal amount, a prediction range with a relatively short operation interval of the soot blower 71, where the dust removal amount removed by one dust removal operation of the soot blower 71 is relatively small and the dust removal amount is at a relatively low level overall (S6).

[0053] <S7: Reduction of operation interval (operation control process)> Then, the operation control unit 75d shortens the operation interval after time t3 compared to the operation interval from time t1 to t3. That is, the operation control unit 75d transmits an operation command signal toward the control panel 72 at the timings of times t4 and t5 at a time interval shorter than the time interval from time t1 to t3.

[0054] When the dust removal amount Q(X) calculated by the dust removal amount calculation unit 75b is greater than the upper limit of the predicted range shown in FIG. 3(a), it is considered that dust has adhered and accumulated excessively on the heat transfer surfaces such as the tertiary superheater 41 beyond the prediction. In such a case, as described above, the interval of the dust removal operation by the soot blower 71 is shortened. In other words, the number of operations of the soot blower 71 within a predetermined time increases. Therefore, even if dust has adhered and accumulated excessively beyond the prediction, the dust can be removed promptly, and the heat recovery performance can be restored promptly.

[0055] <S4~S5,S8~S9> As shown in FIG. 3(b), when the dust removal amount Q(X) immediately after the operation of the soot blower 71 performed at time t3 is outside the predicted range (``NO'' in S4) and the dust removal amount Q(X) is not greater than the upper limit of the predicted range shown in FIG. 3(b) (``NO'' in S5), it is confirmed that the dust removal amount Q(X) is smaller than the lower limit of the predicted range shown in FIG. 3(b). In this case, if the operation command signal has been transmitted from the operation control unit 75d to the control panel 72 at a timing of a time interval shorter than the time interval from time t1 to t3, the transmission timing of the operation command signal from the operation control unit 75d to the control panel 72 is returned to transmit the operation command signal at the same time interval as the time interval from time t1 to t3 (S8~S9).

[0056] <S10~S11: Continuous operation (operation control process)> Then, immediately after time t3, the operation control unit 75d continuously transmits an operation command signal to the control panel 72 multiple times so that the dust removal amount Q(X) calculated by the removal amount calculation unit 75b falls within the prediction range shown in Fig. 3(b) set by the prediction range setting unit 75a. This causes the soot blower 71 to operate continuously. The continuous operation here is a continuous operation including the preparation time as described above, and includes the preparation time required for preparation for the generation of the next pressure wave, but multiple operations are performed continuously as a whole within a predetermined time without intentionally leaving a certain time between the previous operation and the next operation.

[0057] When the dust removal amount Q(X) measured by the removal amount calculation unit 75b is smaller than the lower limit of the predicted range shown in Fig. 3(b), it is considered that dust is firmly attached and accumulated on the heat transfer surfaces of the tertiary superheater 41, etc. In such a case, as described above, the soot blower 71 performs the attachment removal operation multiple times in succession, so that even if the dust is firmly attached and accumulated, the dust can be quickly removed and the heat recovery performance can be quickly restored.

[0058] In the above-mentioned method for removing deposits, if the measured dust removal amount Q(X) is within the predicted range of the dust removal amount even when the soot blower 71 is operated once periodically at a fixed time interval, the soot blower 71 is operated once periodically. On the other hand, if the measured dust removal amount Q(X) is outside the predicted range of the dust removal amount, the operation of the soot blower 71 is controlled in such a way that the interval between the dust removal operations by the soot blower 71 is shortened or the dust removal operations by the soot blower 71 are performed multiple times in succession so that the dust removal amount Q(X) is within the predicted range. Therefore, the soot blower 71 can be operated economically and appropriately, and the amount of dust attached within the predicted range can be reliably removed, and the dust can be sufficiently removed.

[0059] The above describes the adhesion removal system and adhesion removal method of the present invention based on one embodiment, but the present invention is not limited to the configuration described in the above embodiment, and the configuration can be changed as appropriate within the scope of the spirit of the present invention.

[0060] (Another embodiment 1) Fig. 4 is a flowchart showing the procedure of the operation control of the soot blower 71 performed in the dust removal method according to another embodiment 1 of the present invention. As shown in the flowchart of Fig. 4, without performing the operation (S4 to S7: see Fig. 2) performed in the above embodiment to shorten the interval between the dust removal operations by the soot blower 71, when the measured dust removal amount Q(X) is smaller than the lower limit of the prediction range shown in Fig. 3(b), the attachment removal operation by the soot blower 71 may be performed multiple times in succession (S24 to S26) so that the dust removal amount Q(X) becomes equal to or larger than the lower limit of the prediction range shown in Fig. 3(b).

[0061] (Alternative embodiment 2) Fig. 5 is a schematic diagram showing a schematic configuration of a combustion treatment facility 1 equipped with a deposit removal system 70 according to another embodiment 2 of the present invention. In the above embodiment, an example in which the soot blower 71 is disposed in the boiler 4 has been shown, but the present invention is not limited to this. For example, as shown in Fig. 5(a), the soot blower 71 may be disposed in the separately-mounted economizer 5 so that the pressure wave discharge port is located between the second economizer section 52 and the third economizer section 53 in the convection heat transfer chamber 24. Moreover, as shown in Fig. 5(b), the soot blower 71 may be disposed in both the boiler 4 and the separately-mounted economizer 5.

[0062] (Alternative embodiment 3) In the above embodiment and in another embodiment 2 shown in Figure 5 (b), an example is shown in which the soot blower 71 is arranged in the boiler 4 so that the pressure wave discharge port is located between the tertiary superheater 41 and the second turning section 32 in the convective heat transfer chamber 23, but this is not limited to this, and the soot blower 71 may be arranged in the boiler 4 so that the pressure wave discharge port is located between the tertiary superheater 41 and the secondary superheater 42, between the secondary superheater 42 and the primary superheater 43, or between the primary superheater 43 and the third turning section 33.

[0063] (Alternative embodiment 4) In another embodiment 2 shown in Figures 5(a) and (b), an example is shown in which the soot blower 71 is arranged in the separate economizer 5 so that the pressure wave discharge port is located between the second economizer section 52 and the third economizer section 53 in the convection heat transfer chamber 24, but this is not limited to this, and the soot blower 71 may be arranged in the separate economizer 5 so that the pressure wave discharge port is located between the third economizer section 53 and the bottom of the separate economizer 5, between the first economizer section 51 and the second economizer section 52, or between the first economizer section 51 and the third deflection section 33.

[0064] (Alternative embodiment 5) In the above embodiment, the distance L(A) to the dust transported by the transport mechanism 62 is measured using the distance meter 73, and the amount of dust removed by the operation of the soot blower 71, Q(X), is calculated based on the measurement results, but the present invention is not limited to this. For example, there is also an embodiment in which a weight meter such as a load cell that measures the weight of the entire transport device 60 or the entire transport mechanism 62 is provided, and the amount of dust removed, Q(X), is calculated by the removal amount calculation unit 75b based on the change in the measurement value of the weight meter immediately after the operation of the soot blower 71. In this case, the configuration including the weight meter such as the load cell and the removal amount calculation unit 75b corresponds to the "removal amount measurement means" of the present invention.

[0065] (Alternative embodiment 6) In another embodiment, for example, a microwave powder flow meter is provided to measure the flow rate of dust dropping from the second deflection section 32 or the bottom of the separate economizer 5 to the transport device 60, and the dust removal amount Q(X) is calculated by the removal amount calculation unit 75b based on the measurement value of the microwave powder flow meter immediately after the operation of the soot blower 71. In this case, the configuration including the microwave powder flow meter and the removal amount calculation unit 75b corresponds to the "removal amount measurement means" of the present invention. [Industrial Applicability]

[0066] The deposit removal system and method of the present invention can be used in applications such as removing deposits such as soot and dust that are attached to the heat transfer surfaces of heat exchangers, such as boilers, economizers, and air preheaters, that recover heat from exhaust gas generated by the combustion of fossil fuels in thermal power plants, steel mills, oil refineries, and the like, exhaust gas generated by the combustion of waste in waste combustion facilities, and exhaust gas generated by the combustion of biomass fuels in biomass power generation facilities. [Explanation of symbols]

[0067] 1. Combustion treatment facility 41~43 Superheater (heat exchanger) 51~53 Economizer section (heat exchanger) 70 Deposit Removal System 71 Soot Blower 72 Control panel (operation control means) 73 Distance meter (removal amount measuring means) 75 Controller 75a Prediction range setting unit (prediction range setting means) 75b Removal amount calculation unit (removal amount measurement means) 75c Comparison operation unit (operation control means) 75d Operation control unit (operation control means)

Claims

1. A deposit removal system that removes deposits attached to a heat transfer surface of a heat exchanger that recovers heat from exhaust gas using a soot blower, A prediction range setting means for setting a prediction range of the amount of removal of the deposit; A removal amount measuring means for measuring the amount of the deposit removed by the soot blower; An operation control means for controlling the operation of the soot blower so that the measured amount of removed deposit falls within the predicted range; Equipped with The operation control means of the deposit removal system shortens the interval between deposit removal operations by the soot blower when the measured amount of removed deposit is greater than an upper limit of the prediction range.

2. A deposit removal system that removes deposits attached to a heat transfer surface of a heat exchanger that recovers heat from exhaust gas using a soot blower, A prediction range setting means for setting a prediction range of the amount of removal of the deposit; A removal amount measuring means for measuring the amount of the deposit removed by the soot blower; An operation control means for controlling the operation of the soot blower so that the measured amount of removed deposit falls within the predicted range; Equipped with The operation control means of the deposit removal system is configured to perform the deposit removal operation by the soot blower multiple times in succession when the measured amount of removed deposit is smaller than a lower limit of the prediction range.

3. A method for removing deposits attached to a heat transfer surface of a heat exchanger that recovers heat from exhaust gas by using a soot blower, comprising the steps of: a prediction range setting step of setting a prediction range of the amount of removal of the deposit; a removal amount measuring step of measuring the amount of the deposit removed by the soot blower; an operation control step of controlling the operation of the soot blower so that the measured amount of removed deposit falls within the predicted range; Inclusive of An adhesion removal method in which, when the measured amount of adhesion removed is greater than the upper limit of the prediction range, in the operation control process, the operation of the soot blower is controlled so as to shorten the interval between adhesion removal operations by the soot blower.

4. A method for removing deposits adhering to a heat transfer surface of a heat exchanger that recovers heat from exhaust gas by using a soot blower, comprising: a prediction range setting step of setting a prediction range of the amount of removal of the deposit; a removal amount measuring step of measuring the amount of the deposit removed by the soot blower; an operation control step of controlling the operation of the soot blower so that the measured amount of removed deposit falls within the predicted range; Inclusive of An adhesion removal method in which, when the measured amount of adhesion removed is smaller than the lower limit of the predicted range, in the operation control process, the operation of the soot blower is controlled so that the adhesion removal operation is performed by the soot blower multiple times in succession.

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